Creeping tendrils of doom engulf the defenseless victim. Up, up they creep: twining, smothering, eventually dragging their hapless host to its death. The alien lifeform then moves on in search of new prey. Where its colonies thrive, no native can live.
It may be a story best told with a flashlight beneath the chin, but this tale of terror concerns not aliens from outer space, but that insidious alien plant: ivy.
One of Kitsap County’s “Dirty Dozen Noxious Weeds” and certainly near the top of the local weed control board’s least-wanted list, English ivy (Hedera helix) is the dreadnought of invasive species, bringing down even full-grown Douglas firs. Yes, it starts out as a cute little plant in a four-inch pot. “Plant me,” it begs. “I make a great groundcover. I’m evergreen and drought tolerant, and look how small and helpless I am.” But listen to its siren song and before you know it, Seymour is begging to be fed. And Seymour wants to eat the whole forest.
“When ivy grows into thick mats it creates an ‘ivy desert’ where nothing else can grow – native plants can’t penetrate it,” said Kitsap County Noxious Weed Coordinator, Dana Coggon. “It creates a ‘sail’ effect in tall trees. Wind can’t move freely through the branches, which can result in the tree blowing over.”
In addition, ivy restricts the growth of trees making it difficult for them to increase their girth. The heavy vines hold moisture against the bark, promoting fungal diseases – “imagine wearing wet clothes all the time,” said Coggon. Ivy also blocks sunlight and can harbor pests such as rats, mice, and mosquitoes. One thing it does not do, however, is feed off its host.
“It’s a misconception that ivy is saprophytic, sucking nutrients from trees,” Coggon explained. “It gets its nutrition from the ground like most plants. Ivy grows up trees to produce seed. Once it starts up it doesn’t stop until it’s grown all the way to the top.”
In fact, ivy must climb to reproduce. The familiar three- to five-lobed leaves belong to juvenile plants growing on or close to the ground. Once the plants reach a certain elevation, the plants mature and the leaves become “broadleaf” with nearly lobe-less leaves. Flowers are inconspicuous. The berries ripen in early spring and are gobbled up by hungry robins and other birds that spread them throughout the county.
English ivy clings by adventitious roots that adhere to surfaces without actually penetrating them. The entire plant contains noxious substances. The berries and leaves are toxic to humans and even the sap can cause dermatitis and blistering.
The plant is native to Europe and Asia. Ivy is long-lived; reportedly a single plant can survive for hundreds of years. Variegated varieties are less fecund than their green-leafed brethren – being generally slower-growing – but even they need watching.
“Variegates can revert back,” noted Coggon. “All landscape ivies are genetically alike; they’re inherently the same plant. In a couple of areas near Kingston variegates are climbing and becoming broadleaf. But they are less invasive than the straight species.
“With any English ivy, homeowners must be responsible and keep it cut back. The best method is to mow ivy regularly and keep it as a groundcover. Don’t let it grow upwards. That’s when it becomes a gnarly and vicious pest.”
Ivy control: taming the beast
“There’s no silver bullet for getting rid of ivy,” said Dana Coggon, coordinator of Kitsap County’s Noxious Weed program. “First, get it out of trees. Cut the vines in two places: at eye level and down by your toes. Then peel off the cut section. Don’t try to pull the vines out of a tree; it can tear open the bark and make the tree susceptible to disease. And don’t place even a small piece of ivy in your compost pile or it will root. Next, focus on the ground ivy. Create a “ring of life” on the ground around trees, starting at the base of the trunk and removing ivy three feet out in all directions. Try to get as many roots as possible. Then place cardboard over the cleared area and top with three to six inches of mulch. The final rule is to check the area frequently for new starts. It can be a big job, so set a goal to free just one tree a day.”
The best control, said Coggon, is prevention. Never allow ivy to get out of bounds or creep up trees. If you must grow ivy, she recommends mowing it into a groundcover.
Alien invasion of unwanted vegetation
Noxious weeds are defined as non-native plants that displace endemic plant species. Most grow rapidly and are extremely difficult to control. Unfortunately, ivy is just one of a cabal of despotic species that have gone feral in North Kitsap’s woods and wetlands. Dana Coggon of the county’s Noxious Weed Board considers Japanese knotweed (Polygonum ssp.) to be the biggest and most aggressive threat at this time. This pernicious plant is often left to grow by unwitting homeowners attracted by its bamboo-like stems and feathery white flower heads.
“Remember, beauty is only stem deep,” said Coggon. “Up to 60 percent of noxious weeds are escaped ornamentals, and many, such as policeman’s helmet (Impatiens glandulifera) are spread by gardeners passing them along to friends. We each need to take personal responsibility. When it comes to weeds, removing one a day keeps a million away. We can make a big impact if we all pull together.”
Proliferation of the non-ivy leagues
The Great Peninsula Conservancy announces a Kingston ivy pull at their new site on Appletree Cove Oct. 11. For times and parking locations, call the GPC office at (360) 373-3500 or toll free (866) 373-3504. Kate Kuhlman of GPC promises refreshments will be provided. Volunteers are asked to bring handsaws, pruners, and/or short-handled, heavy-duty gardening claws.
The conservancy has sponsored many such pulls at their Waterfront Preserve in Indianola.
“There are quite a few folks involved, and they’ve done an amazing job,” said Kuhlman.
And they aren’t alone: groups of volunteer “pullers” are active in Poulsbo, at Cowling Creek and at the Suquamish Tribal Cemetery. The Weed Warriors of Bainbridge Island are one of the most successful groups in the county.
The Kitsap County Noxious Weed Control Board supports these efforts, and attempts to partner ivy-choked sites with service organizations. Dana Coggon, program coordinator, infuses a little compensation and competition into scheduled ivy pulls with a simple contest: the puller with the biggest pile of weeds has his or her name entered into a drawing. At the end of the year two lucky volunteers will each win a $50 gift certificate to the nursery of their choice.
“If you know of a site with ivy, we’ll work with you to put together an ivy pull,” said Coggon. “And for anyone willing to help, we post weed pulls under Events on our Web site at .
